The invention relates to an electromotive camshaft adjuster for adjusting the angle of rotation of the camshaft of an internal combustion engine relative to the crankshaft thereof.
Electromotive camshaft adjusters are distinguished by quick and exact camshaft adjustment for the entire operating range of the internal combustion engine. This also applies for a cold start and a restart of the internal combustion engine after stalling.
Electrical camshaft adjusters are comprised of an adjustment mechanism connected in a rotationally fixed manner to the camshaft and an electromotive adjusting drive, which is fixed to the adjusting shaft and whose motor shaft attaches to the adjusting shaft of the adjusting mechanism rotating at the camshaft rotational speed.
For the most part, the following triple-shaft gear mechanisms are used as the adjustment mechanism:
Swashplate (or Wobbleplate) Drive.
These drives have a simple construction. Their ability to be manufactured in mass production, however, has not been clarified. In addition, they are susceptible to tolerances, and the manufacture of the teeth parts is associated with high costs, because these parts have to be manufactured with cutting methods due to high loading and for reasons of accuracy.
Double Eccentric Internal Gear Drive.
This type of drive is very functional and quiet running, but generates considerable costs due to the number of components.
Planetary and Cycloid Gears (So-Called Harmonic Drive Gears).
The latter is described in DE 40 227 35 A1, in which an electromotive camshaft adjuster for adjusting the angle of rotation of an internal combustion engine relative to the crankshaft thereof is disclosed, with a triple-shaft transmission, which has a crankshaft-fixed drive wheel constructed as a sprocket or synchronous belt wheel and a camshaft-fixed driven part and also an adjusting shaft, which is connected in a rotationally fixed manner to the rotor of an electric adjustment motor and whose stator is fixed to the internal combustion engine.
This cycloid gear drive is distinguished by low installation space and high function reliability, but requires a large construction expense.
The invention is based on the objective of constructing a triple-shaft gear mechanism for an electromotively driven camshaft adjuster, which provides a relatively low manufacturing expense.